The article “Nonintrusive Appliance Load Monitoring” by George W. Hart, Proceedings of the IEEE, vol. 80, no 12, pages 1870 to 1891, December 1992 discloses an apparatus for nonintrusive appliance load monitoring in an electrical network. The apparatus determines the consumed overall complex power of the electrical network and monitors changes in this complex power. A change in the complex power can be regarded as an event, wherein the apparatus is adapted to compare each event with stored power characteristics of electrical consumers of the electrical network, in order to determine which electrical consumer has caused the actual event. This allows, for example, determining which electrical consumer has been switched on or switched off depending on the consumed complex overall power of the electrical network. However, this apparatus has the disadvantage that it is prone to errors caused by missed events, thereby reducing the reliability of identifying an electrical consumer in the electrical network.